This thesis investigates how the Swedish Military Intelligence and Security Service (Must) discursively constructs and legitimizes the Russian threat in its annual reviews (2014 – 2024). Drawing on critical discourse analysis, Van Leeuwen´s legitimation framework and a critical intelligence studies (CIS) perspective, the study explores how linguistic choices, and discursive practices interact with social structures and power relations. The findings reveal a stable construction of Russia as a threat, initially vague but developing after 2019 into a more explicit threat narrative and legitimized primarily through authorization and rationalization strategies. Must is interpreted from a CIS-perspective, as an authoritative knowledge actor, its discourse narrows the space for alternative interpretations and contributes to reinforce the government’s dominant security agenda. While reinforcing institutional authority, the discourse risks reducing the democratic debate. The thesis argues that greater transparency and reflexivity are essential to balance authority and legitimacy.